1. Field of the Invention
The present invention relates to a magnetic brush developing device to be used in an electrostatic copying apparatus or a facsimile apparatus.
2. Description of the Prior Art
In a conventional electrostatic copying apparatus, a magnetic brush developing device is generally used for developing an electrostatic latent image on a photosensitive member to be used as an electrostatic latent image retaining member a hollow developing roller provided with a magnet roller therein is positioned adjacent to the photosensitive member. A magnetic brush is formed on the surface of the developing roller, and the electrostatic latent image on the photosensitive member is developed visibly by friction with the magnetic brush. In accordance with the conventional magnetic brush developing device as described above, when the magnetic roller stops the magnetic brush which is formed on the surface of the developing roller remains to contact with the photosensitive member, the and developing material adheres mechanically to the surface of the photosensitive member or the surface to be developed. Therefore it is difficult to remove the developing material adhering on the surface of the photosensitive member. Especially, the developing material for pressure fixing has a strong tendency to adhere. Since the surface to be developed is covered with the developing material, i.e. a chemical substance, the surface is subject to chemical change of failure of electrical characteristics.
It is an object of the invention to provide a magnetic brush developing device for solving the technical problems above-mentioned.
A more particular object of the invention is to provide a new and improved magnetic brush developing device to prevent the surface to be developed from changing chemically, or to prevent electrical characteristics of the surface to be developed from failing due to the developing material.